I think this looks good for basic tooltip sizing. I'm not sure it takes into account explicitly set width, though. For example, I tried data-qwidth and it always resized to the content rather than honoring the width I had set. Probably fixable, though - looks like we're getting closer to a real solution.

Yea, should be easy to add that check. Definitely just a temporary solution though.

However, go to any 4.2 example page, fire up the console, and try Ext.supports.Direct2DBug. It returns 0 for me. After setting to true in the console, tooltips start working again in IE10. The amended override I'm trying then is

I tried comparing the the 4.1 and 4.2 sources some more. I think the problem is in the auto container layout somewhere. Between 4.1 and 4.2 A TON of stuff changed. So we can look through this.

In the meantime, as an experiment I tried bringing back the old, simpler auto layout from 4.1 and making it a new container layout that gets applied to tips. This seemed to work well for me in Chrome - better than any of the other workarounds so far since min width is supported and updating tips seems to work. Some of the more esoteric things might not work - for example, the rich content tips in the example aren't quite anchored right. However, I think this might be effective until Sencha gives us a real fix. Might try to dig into auto layout some more to find exact problem... Good luck - hopefully it works out for some people.